The present invention is directed to transmission shifters for motor vehicles, and more particularly to improvements in transmission shifters which control the gear transmission of a motor vehicle via a push-pull cable.
Transmission shifters, whether column mounted or floor mounted are used for operator control of the gear transmission in a motor vehicle. Floor mounted transmission shifters typically the transmission shifter has a shift lever which is mounted on a pivot pin and pivotable over a series of positions: park, reverse, neutral, drive and one or more lower gears, for example. Such transmission shifters can be connected to the gear transmission by, for example, a push-pull cable or electronically. For cable-actuated shifters, tangential motion of the shift lever pulls or pushes on the cable, transmitting load to the gear transmission of the motor vehicle. For proper installation of the shifter and cable there must be a length adjustment mechanism to compensate for variations in distances between cable mounting points. Also, the gear transmission may have some lash, and it is desirable to minimize the lash, preferably by some having some loading placed on the gear transmission from the cable.
In the past length adjustment mechanisms have typically been integrated into the cable assemblies to adjust the length of either the core or the conduit of the cable. However, cable manufacturing is a highly precise process. The more functions a cable needs to perform, the higher the costs associated with its manufacture. Therefore, recently the cable adjustment device has been incorporated into the transmission shifter. In one such known design where the cable adjustment device is incorporated into the transmission shifter, a bracket is mounted around the pivot pin with the shift lever and is provided with a pair of tabs. One tab extends upward and has a cable attachment pin, the other tab is bent over and has a slot. The slot is positioned over a metal yoke extending from the shift lever, and receives a fastening device which can be connected to the bracket at any length along the slot. A spring biases the bracket toward the gear transmission, and the slot accounts for any required length adjustment.
However, this design has several problems. The fastening device must be curved to align with the curved surface of the metal yoke, requiring a specially manufactured part. In addition, both the bracket and the yoke must be lined up with a hole in the base before insertion of the pivot pin, increasing manufacturing complexity. Moreover, vibrational loading can result in aesthetically unacceptable noise and rattle. Accordingly, there is a need for a transmission shifter with a low cost, easy to assembly cable adjustment mechanism that is relatively insensitive to vibrational loading.
In view of the foregoing, it is an object of the present invention to provide a transmission shifter which is of simple construction and low cost, that is highly reliable in operation, and that can be manufactured efficiently while maintaining high quality and reliability in shifting. It is an additional object of the present invention to provide a transmission shifter of quiet operation. Additional objects and optional features of the invention will be apparent form the following disclosure and detailed discussion of preferred embodiments.
In accordance with a first aspect, a transmission shifter comprises a base, a shift lever, mounted on the base and pivotable along a shift path, where the shift lever has a guidance opening. A cable attachment bracket having a tail is adapted to receive a transmission cable. A pin and slot arrangement or other suitable means for adjusting the cable attachment bracket over an adjustment distance is provided, so that the bracket may be adjusted with respect to the shift lever to account for travel lash along the transmission cable. The tail extends into the guidance opening such that the tail is laterally captivated, and the tail cooperates with the pin and slot arrangement to reduce free play between the cable attachment bracket and the shift lever.
In accordance with another aspect a transmission shifter comprises a base, a shift lever, a pivot pin extending through both the shift lever and the base, wherein the shift lever pivots with respect to the base about the pivot pin. A cable attachment bracket is adapted to receive a transmission cable. The cable attachment bracket maybe adjusted over an adjustment distance with respect to the shift lever to account for travel lash and dimensional variance along the length of the transmission cable, and the cable attachment bracket is attached to the shift lever free of the pivot pin.
From the foregoing disclosure and the following more detailed description of various preferred embodiments, it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology and art of shift assemblies. Particularly significant in this regard is the potential the invention affords for reducing overall manufacturing costs of the transmission shifter control of a vehicle. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below.